AI Developer Tools
AI Regex Generator
Describe a pattern in plain English and get a tested regular expression.
Offline engine active
This tool answers immediately from a built-in engine. Connect your own OpenAI-compatible provider for richer answers.
Describe what to match
Generated pattern
Describe the requirement on the left. The offline builder recognises common value types, prefix and suffix requirements, character classes and length ranges, then combines them into one anchored pattern.
About AI Regex Generator
Knowing what to match is easy; expressing it as a regular expression is the hard part. Most requests are variations on a handful of shapes: a value that must look like an email, a number between two lengths, a string that starts with a prefix but not a second one.
Describe the requirement in ordinary language and the offline engine builds a pattern from those intents, explains the pieces, and runs it against any sample text you provide. Because the result is a normal regular expression, you can copy it into the regex tester to check edge cases before using it in code.
How it works
- Your description is tokenised and matched against recognisers for common values such as email, URL, IPv4, ISO date, UUID and hex colour.
- Constraints are extracted from phrases such as starts with, contains, must not contain, digits only and between three and eight characters.
- Detected intents are combined into a single anchored pattern in a deterministic order.
- Each fragment is explained so you can see which part of the expression came from which requirement.
- The pattern is compiled and run against your sample text, showing matches and capture groups.
- With a provider key configured, your description is also sent to your model for an alternative implementation.
Input and output
Accepts
A plain-English description of the pattern and, optionally, sample text to test against.
Produces
A regular expression, an explanation of each fragment, and matches found in the sample text.
Privacy
The offline pattern builder runs in your browser. Descriptions are only sent to a provider when you enable it.
AI Regex Generator FAQ
Is the generated regex safe to use in production?
It is a starting point. Always test it against real inputs from your data set, including the invalid ones, before relying on it for validation.
Why does the pattern include anchors?
Anchors stop a pattern from matching a prefix of a longer string, which is the usual reason a validation rule passes when it should fail.
Which flavour of regular expression is produced?
JavaScript and PCRE-compatible syntax, which also works in most other engines. Named groups and lookbehind may need small changes in Python, Go or Java.
Should I use a regex to validate email addresses?
Only loosely. The specification is far more permissive than any practical pattern; validate structure with a simple expression and confirm deliverability by sending a message.
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